Receiving Object reference not set to an instance of an object error in Site Workflow

I have looked this up on here and nothing really points to my exact issue. I have a site workflow (attached) to where I movie past due items to a past due report and then I clear out specific fields to get it ready for next day. Some items seems to be moving and clearing ok. I have this set to run every night before midnight. Just recently started receiving this error message of Object reference not set to an instance of an object. Not sure what I did to mess it up.

I first query the due date column for any date less than or equal to today. I then run a "For each" action with all of the following in the collection box. Create item into the new past due list (works fine), Calculate current date to add one day, Log in history list. And then I have a update multiple items action (this is where the error is coming from), that I select my current list, filter is set to completed date equal to no, and then I select all of the fields I want to update to blank (I created a blank field template to lookup to for this). The only field I didn't update to blank was due date. I used the variable I created for the calculated date that added 1 day to update due date.

In relation to this...not all of my due date fields are updating to next day after items are moved.

Re: Receiving Object reference not set to an instance of an object error in Site Workflow

I had the same issue where a red ribbon appeared on a workflow edit page, saying that exact message. The workflow was pretty simple. I removed the update item and added it back in. published. error is gone.

Re: Receiving Object reference not set to an instance of an object error in Site Workflow

The only way I've found to work around the issue at least in my case was to check if every field you are updating has data in it. If the field is empty it seemed to cause problems on my end. Unfortunately when I reached out to Nintex their only recommendation was to do a full product upgrade. Too bad they don't offer a patch to resolve such bugs.